Although the preparation of cyclodextrin (CD) monoesters with a variety of carboxylic acids has been already described in the literature, the direct regioselective CD acylation has proved to be critical often, requiring to be replaced with a more elaborate synthetic process. In this paper we describe the one-step preparation of several monoacylated CDs from acyclic or aromatic carboxylic acid derivatives. The ability of beta-CD to enclose cupric ions in a sandwich-type manner was exploited to lead to high regioselectivity in the acylation of beta-CD with benzoyl chloride, cinnamoyl chloride and phenyl acetyl chloride in water. Long chain aliphatic monoesters of alpha-, beta- and gamma-CD were best reared in DMF. The results of our study showed that solvent and general conditions determined an overwhelming regioselectivity of acylation. H-1, C-13 and 2D NMR experiments could easily discriminate the position of the ester. Monoacylated CDs were evaluated as a carrier of silibinin, the inclusion complexes were prepared and characterized by thermal analysis. (C) 2009 Elsevier Ltd. All rights reserved.
Synthesis, characterization and potential application of monoacyl-cyclodextrins
MARTINA, Katia;BARGE, Alessandro;GALLARATE, Marina;CHIRIO, Daniela;CRAVOTTO, Giancarlo
2010-01-01
Abstract
Although the preparation of cyclodextrin (CD) monoesters with a variety of carboxylic acids has been already described in the literature, the direct regioselective CD acylation has proved to be critical often, requiring to be replaced with a more elaborate synthetic process. In this paper we describe the one-step preparation of several monoacylated CDs from acyclic or aromatic carboxylic acid derivatives. The ability of beta-CD to enclose cupric ions in a sandwich-type manner was exploited to lead to high regioselectivity in the acylation of beta-CD with benzoyl chloride, cinnamoyl chloride and phenyl acetyl chloride in water. Long chain aliphatic monoesters of alpha-, beta- and gamma-CD were best reared in DMF. The results of our study showed that solvent and general conditions determined an overwhelming regioselectivity of acylation. H-1, C-13 and 2D NMR experiments could easily discriminate the position of the ester. Monoacylated CDs were evaluated as a carrier of silibinin, the inclusion complexes were prepared and characterized by thermal analysis. (C) 2009 Elsevier Ltd. All rights reserved.
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